Tension-joint for school-desks



2 Sheets- Sheet 1.

(No Model.)

F. Rl BEAL. TBNSIGN JOINT F03 seHooL DBsKs.

Patented Nom 23, 1886.

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2 sheets-sheen 2.

y BRJBML.v TENSION JOINT POR SCHOOL DBSKS.

No. 352,968. Patented Nov. 23, 1886..

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UNITED STATES PATENT". OFFICE.

FRANCIS n'. BEAL, or NCRTIIVILLE; MICHIGAN.

TENSION-JOINT FORfSCHOOL-DESKS.`

SPECIFICATION forming part of Letters Patent No. 352,968, dated November23, 188.6.

Application tiled May 10, 1.886.

' Michigan, haveinvented certain new and useful Improvements inTension-Joints for School- Seats; and I do declare the following to be afull, clear, and lexact description of the invention, such as willenable others skilled in the art to which it appertains to make and usethe sanne, reference being had to the accompanying drawings, and to theletters and figures y of reference marked thereon, which form a part ofthis specication.

This invention relates to certain improvements in the joints to seats ofschool-desks, and especially to that class of seats adapted to be turnedfrom a horizontal to a vertical position and back again.

The great objection to seats heretofore con-A structed has been thenoise in the stopping of the seat wh-en adjusting it and the liabilityof the seat to drop or fall forward when turned up to a verticalposition. By my present arrangement I am able to overcome theseobjections, as I so construct the joint upon which the seat turns thatit tightens as the seat passes back to its vertical position, and againas it assumes its horizontal or normal position. The tension is suchthat the seat will remain in any position desired, all of whichy Iaccomplish by the'mechanism hereinafter set forth; and my inventionconsists in the general -arrangement of parts as hereinafter specified,and pointed out particularly inthe claims.

In the drawings forming a part of this specication, Figure l is aperspective view'of a school seat and desk containing my invention. Fig.2 is an end elevation, having parts broken away. Fig. 3 is an enlargedsection of the seat-joint on dotted line x w of Fig. 2. Fig. 4 is asection of same on dotted line l l of Fig.

2 and dotted line 2 2 0f Figs. 7 and 8. Fig. 5.

is an enlarged rear elevation of the j oint-head K. Fig. 6 is an edgeview of the pressurecap F.4 Fig. 7 is a back face view ofthe locking-capH. Fig. 8 is a back face view of the seat-arm A. Fig. 9 is a view of thesteel disk or spring-plate D.

In the drawings, E is the standard, B the seat-back, and S the'seat.

Serial No. 201,775. (No model.) v

Said arms are journaled on the hub P of the`v j oint-head K of theuprightsor standards E.

In the outer face of the head K, I form an annular chamber, C, with anannular ledge, Z. Fitting insaid chamber and upon said ledge is a squaresteel-disk, D', and'm is a chamber in the head K.

Below or back of the disk D', meeting the front face of the disk'andlying within ythe chamber C', is a Inet-al cap, F, its hub v pressingagainst the center of the disk,'as clearly shownv in Figs. 3 and 4. Thecap Fis provided with a horizontal arm, a, which enters a recess, d, inthe face of the head K, to prevent the cap from turning on thescrew-bolt S', as shown in Fig. 3. The cap F has a horizontal movementin the chamber C', as shown by its position from dotted line of Fig. 3.

The front face of the seat-arm A is provided with an annular chamber, f,which is made sufficiently large to freely iit over the projecting hub Pof the head K, and on said hub the arm turns. (See Figs. 3 and 4.) rIheback face of the arm is provided with two projections or lugs,.' i,having inclined ends t,

' (see Figs. 3 and 8,) with spaces o between the vinclined ends of thelugs i. Y

H is a locking-cap, having its inner face provided with an annularchamber, R, to receive the projections i t' on the back face of the armA.v The bottom of the chamber is provided with projections z" i', lwithinclined ends t, with depressed-spaces o', located between the ends ofthe inclined raised parts i',

the parts being the same as shown on the back face ofthe arm A.

Z is an arm projecting outward at right angles to the face of the cap H,and'when in position, as shown in Figs. l, 2, and 3, engages in therecess c of the head K, whereby said cap is prevented from turning onthe screwbolt S. The back face ofthe cap H is provided with a squarechamber to receive the square nut a, to prevent it from turning as thebolt S is turned to adjust the parts,as willbe hereinafter fullyexplained.

The parts are placed together as follows: The steel disk D is placed inthe chamber G of the head K, and the cap F is then placed in saidchamber, its nose o meeting the face of ICO the disk D. The screw-bolt Sis then passed through the cap F, and the hole e of the disk, thenthrough the hole e in the hub P of the head K. The arm A is then placedwith its chamber f fitting over the hub P. The bolt S passes through thehole e of said arni. l Said bolt is then passed through the hole e ofthe cap H, the arm Z of said cap iitting in the chamber C ofthe head K,as clearly shown in Fig. 3. The nut a is then placed on the bolt S, andby turning the head of said bolt with a screwdriver the parts are firmlybound together. The bolt S is turned suiiiciently to cause the nose o ofthe cap F to press snugly the face of the disk D when the seat-arm A isturned to the dotted position 4 of Fig. 2. When the seat is turned up tothis position, the turning of the arm on the hub I? of the head carriesthe raised portions t' t of the arm A over the depressed surfaces o o ofthe cap H, when the steel disk D will be straight, the cap F thrown outor in the position of Fig. 4. The seat at this point moves freely; butas the seat is thrown back from the dotted position 4 of Fig. 2 to thevertical dotted position of said figure, the arin A, revolving on thesleeve I), brings the raised ledges t' t' in Contact with the projectingledges or lugs t" t" of the cap H, each part riding over the incline tof the other. The additional thickness of theledgesz' t' causes the capH to move back, carrying with it the cap F. lIhe advancing of the capFcauses its nose t to depress the steel disk D', as clearly shown' inFig. 3, thus increasing the tension or pressure against the arrn A as itreaches the vertical position, which prevents the seat from falling backas it is raised. In turning the seat down from the vertical dottedposition of Fig. 2 to the horizontal or normal position of Figs. l and 2the ledges t' t' upon the arm A slide over the ledges i t" of the cap H,then over the depressed portion o' o of said cap, and as the seatassumes its horizontal position the turning of the arm A causes theledges t' t' i i to again meet, when the disk D is again depressed andthe tension increased, whereby the seat is prevented from dropping down,causing a noise, as is corninon with school-seats now in use.

The tension on the disk is regulated byturning the screw-bolt S. TheeXtreme movement of the seat is limited by the stop r r on the arm Ameetingthe shoulders 7i h of the head K, which is common.

Having thus fully set forth my invention, what I claim as new, anddesire to secure by Letters Patent, is-

l.`In a tension-joint for school-seats, the combination of the headhaving the annular chambers and central annular ledge, the springmetaldisk and cap F, located therein, the seatarm having the lugs,withinclined ends'formed on its back face, the cap H, havingthelockingarm Z engaging with the recess C of the head, and lugs t" withinclined ends on its inner face, said lugs adapted to engage with thelugs on the arm A, and the bolt and nut for securing said partstogether.

2. In a tension-joint for school-seats, the combination of ythestandard, the head K,

Aformed integral therewith, the hub P, the

chamber O', having the ledge Z', the springmetal disk, the cap F, havingthe nose 'u and arm a, the seat-arm A, having the chamber f, the lugs t'i, and depressions o o, the cap H, having the arm Z engaging with therecess C of the head, and lugs z t', with screw-bolt se curing saidparts together, as and for the purposes set forth.

3. In a tension-joint for school-seats, the combination of the head K,having the chamber G and annular ledge, the square metal disk located insaid chamber, the arm A, having the lugs t' t with inclined ends anddepressed spaces o 0, the cap H, having the lugs i i', with depressedspaces o o on its inner face, said cap adapted to be locked to the headK, also the cap F, with bolt and nut securing said parts together, asand for the purposes specified.

In testimony whereof I-afx my si gnature in presence of two witnesses.

B. G. WEBSTER, NVM. H. AMBLER.

